All SDK workers have worker_id="1"

SDK workers are created using multiple job factories, which all give their initial workers id 1 [1]. We could perhaps identify sdk workers also by the factory that created them, for example worker_id=$FACTORY-$WORKER (e.g. worker_id="1-1", "1-2"..."2-1"...)

[1] https://github.com/apache/beam/blob/89b08e133be5a2c6bcdbd36242f16ef7ab796902/runners/java-fn-execution/src/main/java/org/apache/beam/runners/fnexecution/control/DefaultJobBundleFactory.java#L115